What exactly is a zip level? What is it used for and how does it work? Is this the perfect new tool to check for foundation problems? You’re looking for pros and cons or advantages and drawbacks here . . .
Maybe you have recently had a home inspector, engineer, or contractor come to your home and use this tool and want to know more about it.
At Anchor Foundation Repair, we have been assessing and repairing sunken and settled crawl space and slab foundations for 35+ years in the Brazos Valley. We can tell you about how we evaluate foundation conditions and let you *gauge* for yourself if this tool is all it is *cracked* up to be or not.
I’m going to be honest with you and say that I am not a user of this particular tool for several reasons that I will talk about. But I will fill you in on the details in as unbiased of a way as possible, just like I do everything else in Our Learning Center.
Our goal is simply to help and empower homeowners to make their own decisions by providing no-nonsense, 100% transparent foundation repair information.
This article will review what a “zip level” is and the basic idea of how it works. We will also discuss the positives and limitations that this tool has in identifying foundation issues in a home. We will also talk about what tools we use to evaluate foundation conditions and why.
What is a Zip Level?
First off, the term ZIPLEVEL® is a brand name that they like to do in all caps. You know how everyone calls all “cotton swabs” Q-tips even if they are not technically the official Johnson & Johnson brand. The generic name for this tool is this: a high-precision altimeter.
So, off I go to my trusty online Merriam-Webster dictionary to find the definition of an altimeter.
Noun: an instrument for measuring altitude
Ok thanks, Webster, that’s not super helpful if you don’t know what altitude is . . .
Noun: the vertical elevation of an object above a surface (such as sea level or land)
So let’s get this out of *dictionar-eese* and say that a high-precision altimeter, like the brand name one called a ZIPLEVEL®, is an instrument that measures the vertical elevation above a surface.
Some might also call it a way to “measure deviation from a level plane”, but then we’re back into complicated language again . . . sheesh.
In the context of your home, this tool would measure the vertical change above or below some point on your foundation compared to another point on your foundation.
The idea here is that you can then theoretically determine if the foundation is sloping. When the two points you are comparing are not at the same elevation or there is a difference between the elevations, then the “zip level” tells you this info.
How Does a Zip Level Work?
This might be hard to explain but I will do my best. The altimeter measures the hydrostatic pressure of a liquid-filled tube that runs between the two points you are measuring. There is a base unit that you set down on the ground or surface–that’s going to be the starting point of any elevation measurements.
Then you pull a smaller part out of the base by a rolled-up line that is stored within the base. The smaller part that gets pulled out is called the “measurement module” and it does the work of measuring and storing the elevation information for later use.
Think of the way a contractor’s tape measure is rolled up, and then you pull on the end and the tape measure unrolls and comes out of the housing.
To measure the elevations in a home foundation, you place the base unit on the floor somewhere inside the house and leave it there. Then you would typically bring just the measurement module with you to each room and take 5 elevation readings per room. One reading in each corner of the room, and one in the middle.
The line can measure up to 200 feet of horizontal distance, and up to 40 feet of vertical elevation. So it can certainly cover the area of a home or property lot.
This data is collected and held in the machine so that maps or diagrams can be created of your home floorplan and show elevations based on each point measured. The stored info is uploaded into specialized software to interpret. Then elevation and contour maps or other useful data outputs can be made for engineers, surveyors, inspectors, or contractors to use.
Pros and Cons of Zip Level Use In Evaluating Foundations
Like everything in life, there are pros and cons or advantages and disadvantages to using these zippy new tools. We will break them down for you here.
Pros of High-Precision Altimeters
- Compact, mobile, and easy for one person to use independently
- One piece of equipment, no tripods, sensors, or extra stuff
- Paper-thin precision measurements of elevation (within 0.050 of an inch)
- No “line of sight” needed to take measurements, easily go from room to room
- Readable without a lot of math or calculations on the part of the user
- Stores the data so that the user doesn’t have to write anything down
These zip-level thingys do offer some great pros, especially for the operator. Easy to use, no math, no partner, no excess equipment. Precise measurements, data storage, and software mapping/interpretation can also come in very handy for a one-man home inspection team.
Just because something is easy and convenient to use, doesn’t mean it doesn’t have some cons too.
Cons of High-Precision Altimeters
- Arbitrary starting point placing the base in the home can yield misleading results
- Calibration issues can result from hot Texas air on a liquid-filled instrument
- Line can get twisted or pinched when out of view and could cause measurement errors
- Differences in flooring types between rooms can yield flawed results
- Room for operator error, relying only on a machine and numbers
- Most homes are built slightly out of level in the first place
Let’s elaborate on that last con because it’s a big-un.
I read a study once showing that American homes averaged about 1.21 inches out of level (I just can’t remember where I saw it otherwise I would put in a link!) Now, you don’t have to be a *super math expert* to understand that an average means that many homes had a higher or lower amount of elevation deviation than that too.
On top of that, it is widely acknowledged and *accepted* in the construction industry and by engineers that elevation deviations are to be expected.
According to the 2015 Post-Tensioning Institute’s Evaluation Guidelines for the Performance of Slab-on-Grade Foundations, “normal construction tolerances for levelness are plus or minus 3/4 inch which means there may be a 1-1/2 inch difference in elevation due to original construction and if within this value then the original construction is within acceptable tolerance.”
Also, the vast majority of homes were not checked using an altimeter at build time, nor were they checked after each home sale. So there is no numeric baseline to compare to when one of these new altimeters is used to measure a home. This device has only started being prevalently used in the last 10 years or so.
On the *surface* a high-precision altimeter sounds like a fantastic and accurate tool to let you know if your foundation is sloped or has experienced settlement. It really does. But often things that make sense in *theory* do not always work in the practical world, especially when it comes to identifying foundation settlement and the need for repair.
What Does Anchor Use to Identify Foundation Issues and Why?
Anchor has been evaluating and repairing foundations since 1985, long before this new technology came on the scene. We feel that there are more reliable, less high-tech tools out there that can determine if you have an unlevel or settled foundation. We use tools that don’t rely on just measurements and nothing else. Let’s check it out.
We Use Our Eyeballs To Identify Signs of Foundation Settlement
There are some very specific cues that signal foundation settlement in a home: things like diagonal cracks in drywall, doors or windows that don’t open, lock, or latch right, and trim boards or fixtures that are separating from their original positions.
Observing telltale signs of foundation problems in a home is the biggest tool we have in our arsenal. While eyeballs are totally free (I mean, I guess unless you have to wear glasses), they are also very precise instruments with a divine design more advanced than any machine.
We can easily see cracks and trim or cabinetry separating from your walls. It’s obvious when a door or window is stuck. A device is not needed when your eyes can tell you that your home has moved or settled.
We Use Feelings and Functionality To Confirm Foundation Problems
Homeowner feelings play a part in determining whether a foundation should be repaired. Homes are supposed to make us feel safe, secure, happy, and (my favorite) cool and dry. If any sign of foundation settlement is making a homeowner feel unsafe, unsecured, unhappy, or unpleasant, then your home is not doing its job and needs to be fixed.
Another big part of determining foundation problems is home functionality. Your home is supposed to “work right” for you. If any signs of settlement cause a functional problem, like a door that won’t open, then that’s an issue that needs repair.
We Use the Tool that Was Used When the Home Was Built
Since we know that a lot of homes have already been built with an average elevation deviation of 1.21 inches and the acceptable deviation limits go up to 1.5 inches, how did anything on your house end up straight?
When most homes were built, the builders used and still use a 4-foot framing level. This is a very effective tool to ensure that the stuff you come face to face with each day is level, square, and plumb (i.e. straight vertical).
Even if your floor surface ends up slightly out of level, builders compensate for these deviations in elevation by making sure all the stuff put on top of your foundation gets put on in a level state. They shim stuff, they lift stuff, they cut stuff to fit. Even when they can’t make everything fit perfectly, they cover it up with trim and make it appear as though it fits perfectly and looks level.
The builders used a level to make sure that your walls were plumb. They made sure that every vertical thing that is placed on your home is plumb and they make sure that any horizontal thing that is placed on your home is level, even when your floor is not level.
A good example here is a countertop or even cabinetry. Let’s say your floor elevation is sloping slightly. But when the cabinets and countertops are installed, they make it level anyway.
Your framing and trim are checked for square and plumb and adjusted at build time. So all the important *bits* should have started out square/level/plumb even if your floor elevation is a little off.
From a historical perspective, we assume that most of the finishes on your home were straight to begin with, even if the floor was slightly sloped. Then we look for changes from there to determine where things have or are moving.
So the massive takeaway here is if something in your home has changed, moved, shifted, sunk, or fallen due to foundation settlement, these home parts that were put on straight at build time will reveal a settlement issue more quickly and reliably than any elevation map of your floor.
Using our eyes we can see the signs of settlement and problems. Using our ears we can hear when people are feeling or saying that their home is not functioning for them. Finally, using the 4-foot framing level, we can confirm the historical story of movement from the home’s original elevation that our eyeballs are already seeing.
Do You Want Your Home Checked for Foundation Problems?
The *bottom line* is that floor elevation and high-precision altimeters do not tell the whole story of your foundation. It’s the signs, feelings, and functionality, combined with history and a level-headed listener that can determine if your foundation has a problem that needs to be repaired.
High-tech tools are only so smart and don’t account for all the compensations and complexity of a home built by and for humans.
At Anchor Foundation Repair, we don’t hide the fact that we are old-school. We’re actually kinda proud of it. We use tried and true methods for both detecting foundation problems as well as repairing them, even when they are not the fastest or the fanciest.